Lubricating oil composition of improved



United States Patent 3,123,570 LUBRICATING OIL CDMPOSITION GF MPROVED LOW-TEMPERATURE DETERGENCY Francis J. Bonner, Wilmington, Dei., and Donald A. Reed,

Gloucester, N.J., assignors to Socony Mobil (Bil Company, Inc, a corporation of New York No Drawing. Filed Dec. 22, 1360, Ser. No. 775%) 3 Claims. (Cl. 252-32.7)

This invention relates to the art of engine lubrication. More specifically, it relates to the improvement of engine lubricating oils from the standpoint of the low-temperature detergency characteristics thereof. Still more particularly, it relates to lubricating oils containing a full formulation of addition agents, including at least one detergent additive plus a relatively minute proportion of an additive which unexpectedly enhances the low-temperature detergency characteristics of the oil composition.

As is weil known, modern engine lubricating oils are fortified with a combination of chemical addition agents designed to enhance the characteristics of the oil in various respects. Thus, such oils generally contain (a) one or more detergents which act to prevent the deposition of sludge or varnish-like coatings resulting from the deterioration of the oil in use on the internal engine surfaces, particularly the piston skirts and ring grooves; (12) one or more antioxidants which act to stabilize the oil against the severe oxidative conditions to which it is exposed in the engine so that its deterioration in use is greatly retarded. The oil usually also contains (0) a viscosity index improver which helps the oil to maintain a constant level of fluidity over a wide range of temperatures to which it is exposed in use. In addition, depending upon the conditions of use for which the oil is designed, it may contain in addition pour point depressants, metal deactivators, defoamants, etc.

The type of chemical compounds which serve as additives to improve the oil in the aforesaid respects are well known to the art. The present invention, however, is concerned with an oil composition containing a combination of specific types of additives which are recognized in the art as providing an engine lubricating oil of socalled premium grade. Specifically, this oil contains the following combination of additives, viz., (a) a barium sulfonate detergent, (b) a complex carbonated metal phenate sulfide detergent, and (c) a zinc dialityl dithiophosphate antioxidant. The oil also contains a viscosity index and pour point improving additive of the well known polymethylmethacrylate type, the presence of which in the oil composition, however, is not critical to and does not form part of the invention.

It has been found in accordance with the invention that although the afore-described oil composition exhibits excellent antioxidant characteristics and excellent detergency characteristics from the standpoint of inhibiting deposition of engine deposits resulting from the so-called hightemperature conditions encountered in use, it is not fully satisfactory from the standpoint of preventing the formation of engine deposits resulting from low-temperature operating conditions. These latter, low-temperature deposits are recognized in the art as resulting specifically from operating conditions referred to in the art as stopand-go driving. Thus, under these conditions, which are frequently encountered in normal automobile use, the engine does not obtain a full warm-up and it has been recognized that such low-temperature, intermittent, operation causes engine deposit problems which are not counteracted by the detergent and antioxidant additives.

It has now been found, in accordance with the present invention, that a premium grade engine lubricating oil containing a combination of detergent and antioxidant additives, such as that outlined above, can be markedly improved with respect to its low-temperature detergency characteristics by the addition thereto of a relatively minute amount of an alkylphenylpolyethoxyethanol of the general formula wherein R is an alkyl radical having from 4 to 12 carbon atoms, such as butyl, octyl, dodecyl, etc., and x is an integer of from 7 to 9. These alkylphenylpolyethoxyethanols are well known in the art and are formed by the reaction of ethylene oxide with alkylphenols.

The alitylphenylpolyethoxyethanol compounds of the invention have not been recognized heretofore as having any engine oil-detergency characteristics and, indeed, when added to an oil by themselves exhibit no such characteristics in the oil. It has now been found, however, that when these compounds are added in only a minute amount to a fully formulated oil of the afore-described character, they provide an unexpected improvement in the low-temperature detergency characteristics of the oil.

It is, therefore, the primary object of this invention to provide an engine oil composition of enhanced low-temperature detergency characteristics, said composition containing a combination of detergent and antioxidant additives pius a minute proportion of an alkylphenylpolyethoxyethanol compound of the afore-defined character. Other and further objects will appear from the following detailed description of the invention. The invention will be fully understood by reference to the following examples and tests.

CHEVROLET FL-Z TEST This test simulates low-temperature, stop and go service conditions. The test determines the effectiveness of a lubricating oil in inhibiting the formation of engine deposits under these conditions. In accordance with the test a Chevrolet 216 cu. in. 6-cylinder overhead valve engine with tin-plated pistons is operated under the following conditions:

Starting with a perfectly clean engine, a piston varnish and sludge deposit rating is obtained by disassembly of the engine and inspection of the piston after completion of the test using the CRC L4 rating method. By this means a perfectly clean engine would rate 100, while 0 would indicate the worst possible deposit condition.

Example 1 A fully compounded premium-grade motor oil was prepared as follows: To a base oil composed of solvent-refined parafiinic neutral and 20% solvent-refined naphthenic stock and having an SUV of 31.5 seconds F., there was added the following:

(a) 3.0% by weight, of a commercial barium sulfonate detergent additive consisting of a 55% solution in mineral oil of a barium salt of an alkylaryl sulfonic acid having an average molecular weight of about 450 and prepared by sulfonating a mixture of long-chained, i.e., C and higher, alkyl-substituted benzenes comprised predominantly of paraffin wax-substituted benzenes. The additive oil concentrate analyzed 10% barium;

(b) 3.3% by weight, of a barium phenate sulfide detergent additive consisting of a 30% oil solution of a complex carbonated barium phenate salt of a nonylphenol sulfide. This class of barium phenol sulfide salt additives is fully disclosed in US. Patent No. 2,916,454, issued December 8, 1959, to John S. Bradley V et al. The instant additive was prepared after the fashion of Example 1 of the said patent, the product oil solution being diluted with oil so as to provide a barium content therein of 10%;

(c) 0.75%, by weight, of a commercial antioxidant additive consisting of an 85% oil solution of zinc dihexyl dithiophosphate. The conwntrate analyzed 9.5% zinc; and

(d) 6.5%, by weight, of a commercial viscosity index improving additive'of the polymethacrylate ester type.

The above-compounded oil composition when subjected to the Chevrolet FL2 test gave a piston varnish rating of 37.

Example 2 To the fully compounded oil of Example 1, there was added 0.2%, by weight, of the alkylphenylpolyethoxyethanol compound nOnylphenyl-O- CHgCHgOH This oil when subjected to the Chevrolet FL-2 test gave a piston varnish rating of 83.

Example 3 An oil composition containing all of the additives of Example 2, except the viscosity index improver, was subjected to the FL-Z test. This oil gave a piston varnish rating of 83. Accordingly, it is evident that the improvement in low-temperature detergency provided by the alkylphenylpolyethoxyethanol does not depend on the presence of the viscosity index improving additive in the oil.

Example 4 An FL-2 test was conducted on an oil containing all of the additives of Example 2, except the barium sulfonate additive. This oil gave a piston rating of only 45.

Example 5 An oil containing all of the additives of Example 2, except the carbonated barium nonylphenol sulfide detergent, was subjected to the FL-2 test. The piston rating was only 43.

Example 6 An oil containing all of the additives of Example 2, except the zinc dihexyl dithiophosphate antioxidant was tested. The piston rating was only 55.

Example 7 A further test was conducted on an oil composition similar to that of Example 2, except that the alkylphenolpolyethoxyethanol compound of Example 2 was replaced by the compound nonylphenyl-O(CH CH O) CH CH OH This oil gave a piston rating of 87.

From the foregoing test results, it is seen that the use in the fully formulated oil of only a minute proportion, i.e., 0.2 weight percent, of the alkylphenylpolyethoxyethanol compounds (Examples 2 and 7) provided a marked improvement in the low-temperature detergency characteristics of the oil, but that this improvement is not obtained if any one of the two detergent additives or the antioxidant additive is omitted (Examples 4, 5 and 6). It is seen then that the improvement in the low-temperature detergency characteristics of the oil derives from the presence therein of these latter three additives and the alkylphenylpolyethoxyethanol compound.

Although the principle or" the invention is demonstrated in the foregoing examples by means of specific additives, it will be appreciated by those skilled in the art that equivalent additives of the barium sulfonate, barium phenol sulfide and zinc dithiophosphate types can be utilized in the oil to be improved by the addition of the alkylphenyl polyethoxyethanol in place of the specific additives shown in the foregoing examples. Thus, the barium sulfonate additive may be derived from either petroleum sulfonic acids (i.e., mahogany acids) or oil-soluble synthetic alkylsubstituted aryl sulfonic acids, the general class of suitable acids being represented by the formula carbon atoms, such as, for example, octylphenol sulfide,

nonylphenol sulfide, dodecyl phenol sulfide, hexadecyl phenol sulfide, octadecyl phenol sulfide and Wax phenol sulfide, being particularly preferred, This class of carbonated barium phenol sulfides are disclosed in detail in US. Patent No. 2,916,454.

Also, the principle of the invention is not limited to the use of the zinc dihexyl dithiophosphate salt additive utilized in the foregoing examples, but this salt may be substituted for by other Well-known zinc dialkyl dithim phosphate salt antioxidants, such salts having alkyl substituent radicals of from 4 to about 20 carbon atoms. Zinc salts of this character are disclosed in various patents, such as, for example, US. Patents Nos. 2,364,283, 2,680,- 123 and 2,689,220.

Although specific amounts of the detergent and antioxidant additives were employed in the examples presented herein for the purpose of illustrating [the principle of the invention, it will be appreciated that the amounts of these additives used can be varied within practical limits without substantial lessening of the low-temperature de-tergency improving elfect provided by the invention. Thus, the barium sulfonate and complex carbonated barium phenol sulfide additives may be used at concentrations of from about 0.5 to about 10%, by Weight, the preferred amount being from 1% to about 5%, While the zinc dialkyl dithiophosphate additive may be used at concentrations of from about 0.1% to about 5.0%, by Weight, preferably from about 0.5% to about 2.0%.

Likewise, although for purpose of comparison the examples presented herein show the use of 0.2%, by Weight, of the alkylphenylpolyethoxyethanol compound in the compounded oil, the use of as little as 0.01% thereof will provide a significant improvement in the lowtemperature detergency characteristics of the oil composition. The upper limit of amount of this compound which can be used is not critical, but will be governed by the solubility thereof in the oil. Thus, although the contemplated alkylphenylpolyethoxyethanols are by themselves only very slightly oil-soluble, their solubility is greatly enhanced by the barium sulfonate additive, clear solutions of amounts up to about 1%, or more, being obtainable in the presence of 10% of barium sulfona-te. In general then, the amount of the alkylphenylpolyethoxyethanol to be used will be from about 0.01% to about 1.0%.

The oil compositions of the invention may also contain other additives than those described herein for the purpose of improving the oil in other respects, such as extreme pressure agents, pour point depressants, foam inhibitors, etc.

What is claimed is:

1. A motor oil of improved low-temperature detergency characteristics comprising a major proportion of lubricating oil and (a) from about 0.5 to about 10.0%, by weight, of a barium salt of an oil-soluble sulfonic acid, (b) from about 0.5 to about 10% of a complex carbonated barium phenate salt of an alkylphenol sulfide, (c)

5 from about 0.1% to about 5.0% of a zinc dialkyl dithiophosphate, and (d) from about 0.01% to about 1.0% of a compound of the formula:

) CH CH OH where R is an alkyl radical of from 4 to 12 carbon atoms and x is an integer of from 7 to 9, inclusive.

2. A motor oil of improved low-ternperature detergency characteristics comprising a major proportion of lubricating oil and (a) from about 0.5% to about 10.0%, by weight, of a barium salt of an oil-soluble sulfonic acid, (b) from about 0.5% to about 10% of a complex carbonated barium phenate salt of an alkylphenol sulfide, (c) from about 0.1% to about 5.0% of a zinc dialkyl dithiophosphate, and (d) from about 0.01% to about 1.0% of the compound,

nonylphenyl-O- (CH CI-I O CH C-H OH 3. A motor oil out improved low-temperature deterency characteristics comprising a major proportion of lubricating oil and (a) from about 0.5% to about 10.0%,

6 by Weight, of a barium salt of an oil-soluble sulfonic acid, (b) from about 0.5% to about 10% of a complex carbonated barium phenate salt of an alkylphenol sulfide, (c) from about 0.1% to about 5 .0% of a zinc dial-kyl dithiophospna-te, and (d) from about 0.01% to about 1.0% of the compound,

References Cited in the file of this patent UNITED STATES PATENTS 2,402,969 McCleary July 2, 1946 2,485,150 Glav-is Oct. 418, 1949 2,681,315 Ton-g berg et al. June 15, 1954 2,850,455 Kern et al. Sept. 2, 1958 2,916,454 Bradley et a1 Dec. 8, 1959 2,964,473 Hughes et a1 Dec. 13, 1960 FOREIGN PATENTS Canada June 5, 1956 

1. A MOTOR OIL OF IMPROVED LOW-TEMPERATURE DETERGENCY CHARACTERISTICS COMPRISING A MAJOR PROPORTION OF LUBRICATING OIL AND (A) FROM ABOUT 0.5% TO ABOUT 10.0%, BY WEIGHT, OF A BARIUM SALT OF AN OIL-SOLUBLE SULFONIC ACID, (B) FROM ABOUT 0.5% TO ABOUT 10% OF A COMPLEX CARBONATED BARIUM PHENATE SALT OF AN ALKYLPHENOL SULFIDE, (C) FROM ABOUT 0.1% TO ABOUT 5.0% OF A ZINC DIALKYL DITHIOPHOSPHATE, AND (D) FROM ABOUT 0.01% TO ABOUT 1.0% OF A COMPOUND OF THE FORMULA: 